[postgis-users] Intersection TopologyException

[Rémi Cura]

Hey,
some common answer about precision issue :


1. : offset your coordinate to gain in precision :
723120.23091093975 4379700.195452339 -> 120.23091093975XXX ,
700.195452339XXXX
2. snap to grid you input data

3. check that your input geoms are valid : st_isvalid : st_makevalid()

Cheers,
Rémi-C

2014-12-02 11:45 GMT+01:00 Luís Miguel Royo Pérez <
luis.miguel.royo at gmail.com>:

>  Hi everyone,
>
> I'm trying to perform a quite simple analysis in Postgis, but I'm facing a
> TopologyException where there's no features.
>
> You can find the data I'm using in this link
> <https://mega.co.nz/#%21pFgnCBoA%21zx-Tb78nPGzL7Fcbw7dMheSbIrMfRJjJ9yV1Qv7Wx6o>
> .
>
> What I try to do is the next:
>
>    - First I want to create a buffer for emt_paradas, and the layer
>    valenbisi, and then intersect them, the result I will call "intersect_1".
>
>     select  st_intersection(buf_emt.st_union,buf_valenbisi.st_union)
>     from
>     (SELECT  ST_union(st_buffer(emt_paradas.geom, 200)) FROM emt_paradas )as buf_emt,
>     (SELECT  ST_union(st_buffer(valenbisi.geom, 200)) FROM valenbisi )as buf_valenbisi
>
>
>    - Second, I want to create a buffer for carril_bici, and intersect
>    with "intersect_1". The result I will call "intersect_2".
>
>     select  st_intersection(buf_carril_bici.st_union,inter_emt_valenbisi.st_intersection)
>     from
>     (select  st_intersection(buf_emt.st_union,buf_valenbisi.st_union)
>     from
>     (SELECT  ST_union(st_buffer(emt_paradas.geom, 200)) FROM emt_paradas )as buf_emt,
>     (SELECT  ST_union(st_buffer(valenbisi.geom, 200)) FROM valenbisi )as buf_valenbisi) as intersect_1
>
>
>    - Third, I want to create a buffer for layer ocio and make a
>    difference with "intersect_2". The result I will call: "diff_1".
>
>     select  st_difference(intersec_2.st_intersection, buf_ocio.st_union)
>     from
>     (select  st_intersection(buf_carril_bici.st_union,inter_emt_valenbisi.st_intersection)
>     from
>     (select  st_intersection(buf_emt.st_union,buf_valenbisi.st_union)
>     from
>     (SELECT  ST_union(st_buffer(emt_paradas.geom, 200)) FROM emt_paradas )as buf_emt,
>     (SELECT  ST_union(st_buffer(valenbisi.geom, 200)) FROM valenbisi )as buf_valenbisi) as inter_emt_valenbisi,
>     (SELECT  ST_union(st_buffer(carril_bici.geom, 200)) FROM carril_bici )as buf_carril_bici) as intersectionEMT_valenbisi_carrilBici,
>     (SELECT  ST_union(st_buffer(ocio.geom, 250)) FROM ocio )as buf_ocio
>
>
>    - Finnaly I want to intersect "diff_1" with layer mapa_ruido_dia,
>    ideally where the field gridcode equals one or two.
>
>     select 1 as id, st_intersection(diff_1.st_difference, mapa_ruido_dia.geom)
>     from
>     (select  st_difference(intersectionEMT_valenbisi_carrilBici.st_intersection, buf_ocio.st_union)
>     from
>     (select  st_intersection(buf_carril_bici.st_union,inter_emt_valenbisi.st_intersection)
>     from
>     (select  st_intersection(buf_emt.st_union,buf_valenbisi.st_union)
>     from
>     (SELECT  ST_union(st_buffer(emt_paradas.geom, 200)) FROM emt_paradas )as buf_emt,
>     (SELECT  ST_union(st_buffer(valenbisi.geom, 200)) FROM valenbisi )as buf_valenbisi) as inter_emt_valenbisi,
>     (SELECT  ST_union(st_buffer(carril_bici.geom, 200)) FROM carril_bici )as buf_carril_bici) as intersectionEMT_valenbisi_carrilBici,
>     (SELECT  ST_union(st_buffer(ocio.geom, 250)) FROM ocio )as buf_ocio)as diff_1, mapa_ruido_dia
>      where mapa_ruido_dia.gridcode='1' or mapa_ruido_dia.gridcode='2'
>
>
> Is in this last one query when Postgis show me the TopologyException
>
> > Error performing intersection: TopologyException: Input geom 1 is
> > invalid: Self-intersection at or near point 723120.23091093975
> > 4379700.195452339 at 723120.23091093975 4379700.195452339
>
> Any ideas? Thank you very much!
>
>
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